This was the war diary of Otto Kretschmer, commanding U-99, for the period around midnight 18th/19th October:

18.10

2330. Now attacking right wing of the last line but one. Bow shot at a large freighter. The vessel zig-zagged, with the result that the torpedo passed in front of her and hit instead her even bigger neighbour after a run of 1,740 yards. The ship, about 7,000 tons, was hit below the foremast and sank quickly by the bows with, I presume, two holds flooded.

2358. Bow shot at large freighter approx. 6,000 tons. Range 750 yards. Hit below foremast. The explosion of the torpedo was immediately followed by a high sheet of flame and an explosion which ripped the ship open as far as the bridge and left a cloud of smoke 600 feet high. Ship’s forepart apparently shattered. Ship still burning fiercely, with green flames.

19.10

0015. Three destroyers, line abreast, approach the ship, searching the vicinity. I went off at full speed on a south-westerly course and very soon regained contact with the convoy. Torpedoes from other boats exploding all the time. The destroyers are at their wits’ end, shooting off star shells the whole time to comfort themselves and each other. Not that that makes much odds in the bright moonlight. I am now beginning to pick them off from astern of the convoy.

Those U-boats that still had torpedoes following the attack on Convoy SC7 were now ordered to join up with U-47, commanded by Gunther Prien. He had spotted another Liverpool bound convoy, this time unescorted. Although the Royal Navy, alarmed at the losses to SC7 and aware of the probable danger to HX79 sent ships to the scene, they were no deterrent to the night time attack by the Wolfpack.

After leaving the remains of HX79, the U Boats went on to attack an outward bound convoy from Britain – HX79A – and sank a further seven ships on the night of the 20th/21st.

It was a terrible period for the Royal Navy, despite having the escort ships on the scene of the action, they had been unable to prevent a determined night attacks by U-boats on the surface in the middle of convoys.

Gunther Prien, the German U-boat ‘ace’.

The star of the German show was once again Gunther Prien who provided another great propaganda boost for the the Nazis. His tonnage sunk may well have been exaggerated to push him along. He was now awarded the Oak Leaves to the Knights Cross.

The entire crew of 40 were saved from the merchant steam ship Uganda when it was sunk on the 19th October 1940, possibly by U-47 commanded by Gunther Prien.

Meanwhile Admiral Karl Doenitz, directing the U-Boat war, felt that his tactics had been vindicated. As he afterwards recorded in his memoirs:

In three days, then, and almost exclusively in night attacks delivered together, eight boats had sunk thirty-eight ships belonging to three different convoys. In these operations no U-boat was lost.

The conclusions to which I came and which I entered in my War Diary were:

1. These operations have demonstrated the correctness of the principle which since 1935 has governed the development of U-boat tactics and been the basis of all U-boat training, namely, that the concentration which a convoy represents must be attacked by a like concentration of U-boats acting together. This has become possible thanks to the advances made in means of communication.

2. It is only possible to carry out attacks of this kind when captains and crews have been thoroughly trained for the purpose.

3. They are only possible when the requisite number of U-boats are present in the area in question.

4. The greater the number of U-boats in any given area of operations, the more likely it becomes that with more eyes (i.e. more U-boats) more convoys will be spotted – and the more numerous will become the opportunities for these concerted attacks.

5. Again, the presence of a greater number of U-boats means that, after an attack of this kind, the sea lanes of approach to Britain will not be free of danger for the time being. At the moment, nearly all the operational U-boats, after having exhausted their load of torpedoes, are forced to return to their base.

6. Success such as was achieved in the operations under review cannot always be expected. Fog, bad weather and other factors can sometimes completely ruin all prospects of success.

The decisive factor, however, is, and always will be, the ability of the captains and their crews.

Follow the war as it happened …

Updated 75 years after the event…

“The German Army at this time was probably the most formidable and effective fighting machine since the Roman legions. Immensely battle-experienced in Poland, the fall of France, North Africa, Italy and, above all, Russia; superbly well-equipped, intensely fanatical and, above all, literally fighting for their lives and future…”